<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  background: #222;
  margin: auto;
  width: 960px;
}

.arc-text {
  font: 16px sans-serif;
}

.arc-center {
  fill: none;
}

#credit {
  position: absolute;
  font: 10px sans-serif;
  right: 10px;
  bottom: 10px;
  color: #ddd;
}

#credit a {
  color: inherit;
}

</style>
<div id="credit">Found on <a href="https://d3js.org/"> d3js.org </a></br>
Inspired by <a href="http://blog.pixelbreaker.com/polarclock/">pixelbreaker</a>.</div>
<script src="https://d3js.org/d3.v3.min.js"></script>
<script>

var width = 960,
    height = 800,
    radius = Math.min(width, height) / 1.9,
    spacing = .09;

var formatSecond = d3.time.format("%-S seconds"),
    formatMinute = d3.time.format("%-M minutes"),
    formatHour = d3.time.format("%-H hours"),
    formatDay = d3.time.format("%A"),
    formatDate = function(d) { d = d.getDate(); switch (10 <= d && d <= 19 ? 10 : d % 10) { case 1: d += "st"; break; case 2: d += "nd"; break; case 3: d += "rd"; break; default: d += "th"; break; } return d; },
    formatMonth = d3.time.format("%B");

var color = d3.scale.linear()
    .range(["hsl(-180,60%,50%)", "hsl(180,60%,50%)"])
    .interpolate(function(a, b) { var i = d3.interpolateString(a, b); return function(t) { return d3.hsl(i(t)); }; });

var arcBody = d3.svg.arc()
    .startAngle(0)
    .endAngle(function(d) { return d.value * 2 * Math.PI; })
    .innerRadius(function(d) { return d.index * radius; })
    .outerRadius(function(d) { return (d.index + spacing) * radius; })
    .cornerRadius(6);

var arcCenter = d3.svg.arc()
    .startAngle(0)
    .endAngle(function(d) { return d.value * 2 * Math.PI; })
    .innerRadius(function(d) { return (d.index + spacing / 2) * radius; })
    .outerRadius(function(d) { return (d.index + spacing / 2) * radius; });

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
  .append("g")
    .attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");

var field = svg.selectAll("g")
    .data(fields)
  .enter().append("g");

field.append("path")
    .attr("class", "arc-body");

field.append("path")
    .attr("id", function(d, i) { return "arc-center-" + i; })
    .attr("class", "arc-center");

field.append("text")
    .attr("dy", ".35em")
    .attr("dx", ".75em")
    .style("text-anchor", "start")
  .append("textPath")
    .attr("startOffset", "50%")
    .attr("class", "arc-text")
    .attr("xlink:href", function(d, i) { return "#arc-center-" + i; });

tick();

d3.select(self.frameElement).style("height", height + "px");

function tick() {
  if (!document.hidden) field
      .each(function(d) { this._value = d.value; })
      .data(fields)
      .each(function(d) { d.previousValue = this._value; })
    .transition()
      .ease("elastic")
      .duration(500)
      .each(fieldTransition);

  setTimeout(tick, 1000 - Date.now() % 1000);
}

function fieldTransition() {
  var field = d3.select(this).transition();

  field.select(".arc-body")
      .attrTween("d", arcTween(arcBody))
      .style("fill", function(d) { return color(d.value); });

  field.select(".arc-center")
      .attrTween("d", arcTween(arcCenter));

  field.select(".arc-text")
      .text(function(d) { return d.text; });
}

function arcTween(arc) {
  return function(d) {
    var i = d3.interpolateNumber(d.previousValue, d.value);
    return function(t) {
      d.value = i(t);
      return arc(d);
    };
  };
}

function fields() {
  var now = new Date;
  return [
    {index: .7, text: formatSecond(now), value: now.getSeconds() / 60},
    {index: .6, text: formatMinute(now), value: now.getMinutes() / 60},
    {index: .5, text: formatHour(now),   value: now.getHours() / 24},
    {index: .3, text: formatDay(now),    value: now.getDay() / 7},
    {index: .2, text: formatDate(now),   value: (now.getDate() - 1) / (32 - new Date(now.getYear(), now.getMonth(), 32).getDate())},
    {index: .1, text: formatMonth(now),  value: now.getMonth() / 12}
  ];
}

</script>
